Background: The increase in obesity has become a major public health concern. Morbid obesity is associated with co-morbidities, reduced quality-of-life, and death. Metabolic surgery (MS) is the most effective treatment for obesity. Objectives: The aim of this study was to evaluate the costs and outcomes of MS compared with no surgery in patients with a body mass index >= 30 kg/m(2). Setting: Health care system, Austria Methods: A total of 177 patients who underwent MS were documented retrospectively, based on the hospital records of 2 specialized centers in Austria, over a 1-year period. At baseline 26.0% of patients exhibited type 2 diabetes (T2D), 52.5% cardiovascular disease (CVD), 23.2% hyperlipidemia, and 23.7% depression. Following the observation period, a Markov chain simulation model was developed to analyze the long-term consequences of T2D, including diabetic complications, CVD, hyperlipidemia, depression, non-alcoholic steatohepatitis (NASH), myocardial infarction, and stroke, over a total of 20 years. Direct medical costs were expressed in 2017 euros from the payer's perspective. Quality-adjusted life years (QALYs), life years (LYs), and costs were discounted. Results: MS led to costs of (sic)40,427 and 9.58 QALYs (15.58 LYs) per patient over 20 years. No MS was associated with (sic)64,819 and 6.33 QALYs (13.92 LYs). Total cost-savings amounted to (sic)24,392, which offset the cost of the procedure including re-operations. Over 20 years MS saved -6.7 patient-years per patient with T2D, -5.8 patient-years with CVD, -1.5 patient-years with hyperlipidemia, -1.8 patient-years with depression, and -3.8 patient-years with NASH. Conclusion: MS is associated with substantial savings in long-term costs, expected health benefits, and reduced onset of complications. MS significantly increases quality of life. (C) 2021 American Society for Bariatric Surgery. Published by Elsevier Inc.